Spark plug



March 6, 1928. 1,661,405

B. BROLUSKA SPARK PLUG Filed Jan.l7, 1925 INVENTOR.

A TT ORNE Y.

ductivity of metal than other material. Thls construction obviates an expensive or at least anexcessively high heat resistent insulating material being used throughout their deposit in the plug the construc ion as it is only necessary to have the very best type in the thimble construction. The feature of construction is forming the lower end of the insulating body with the frustro-eonical cavity is a means for more adequate and positive insulation due to hot spotting the upper thimble insulating surface and makes possible the rapid drying up or vaporizing of oil, gasoline, carbon, and other matter thrown by the piston on this surface. The thimbles frustro-eonical upper form furnishes a large area and the inclined surface presented to the oil, etc, thrown by inertia, or the turbulence of the gas, prevents to a large extent and insures their being expelled with the exhaust. The thimble flange also acts as a seal against coinpression leakage through the plug and its consequent resultant heating of the plug as well as insulating the electrodes if desired F or the flange may be cut away to allow passage of the electrodes. The flange edges aid greatly as an insulator. Short-circuiting of the current is practically impossible as the insulator prevents the accumulation of oil,

carbon, dirt and other matter that will cling and form on a cooler metal surface and which deposit causes short-c rcuit1ng, preagmtron, missing and to which more than half of the spark plug failures are due.

Such chunks of carbon deposit mayjeven cause an open circuit when they get vibrated loose and lodge between the firing points. The insulating flange prevents the oil film forming and so eliminates the ring of car.- bon on the lower edge of the plug, in this construction and exposes no metal at the edge or plugcavity to the direct action of the combustion chamber, yet provides one of the highest resistent insulations and means for maintaining its eficiency. d is a small aperture formed through the upper end of the thimble cl, coaxial with the a erture of. j is a conducting rod, exten ing' coaxially through the aperture a, and provided with screw threads at its upper end that extend beyond the upper end of the porcelain a. j is a circular flange or disc on the rod 3', fitting against the under side of the upper end of the thimble al. 9' is, a.

disc on the lower end of the rod j, and the upper side of said disc tapers upward into said electrode in the form of a cone. This construction prevents the rapid cooling and also the intense heating of the disc edge.

This disc acts as a shield and heat reservoir flange of the thimble cl formed by the turning over ofthe lower edge of said thimble upon the lower edge of the sleeve 6.

The rod 7' is passed through the aperture d its flange y' engaging the upper end of the thimble d, and the disc j coming just below the inner ends of the sparking points, 6 and 5 its screw-threaded end extending above the porcelain a. The upper surface of the disc is a tapered incline and carbonization at the arcing points and on the electrode is prevented for the oil runs down the inclined stem. The upturned ends of the electrodes 6 25 permits the oil to run from the ends and the sparking gap distance is exactly maintained.

e is a metal cap having its'peripheral edge turneddownward at e to engagethe outerwall at the upper end of the porcelain a.

against the upper and lower surfaces of the cap '6. g is a metal nut screwed-yupon the rod j, and engagingabove the washer f.. 7c

is a conductor wire having the usual terminal 76 around the rod and engaging upon the upper surface of the nut g. a nut engaging upon the upper end of the hlst rod 7' and acting the clamp the terminal 70 against the nut 9, so as to connect said terminal-with the rod 3":

It will be observed that the rod j and connected parts arecompletely insulated from the porcelain 0a.

It will also be noticed that the terminals of the sparking points are protected-and shielded by the disc, P, so that they are notso liable to receive a deposit from the charge. The porcelain a is not as close to the source of heat as in the usual-ron stru'etion, and apertures, 5 0 are provided to permit the escape of heat from the porcelain and maintains a lower and moreconstant temperature level. Tn Figure 6, the rod j is bent over in a part I), and terminates in a ball. b? is a menses terminating in a ball that is vertically above the ball at the part 6 in Figure 7, the part is bent over and terminates in an extended edge and the part 6 extends vertically downward above the terminal of the part 5 The terminal part 5 has a projection rising at each end of its upper edge so that it presents the appearance of a fork, as shown in the drawing. T he part extends between these projections or in the hollow of the fork and terminates in saw teeth its lower end.

ln Figure 8, the part j is bent sideways in a part W and extends below the vertically downwardly extending part, 6 and then bends over and terminates at a point near the outer surface of the part, 5

In these three modified constructions. the upper terminal is protected by the lower terminal arranged just below it.

ln the forms of the device shown in Figures l and 8, there are two points at which the spark may pass between the electrodes thus forming a multiple are.

I prefer to place mica washer between the cap 6 and the upper end of the porcelain a, to position the rod at its upper end, and to additiona ly seal possible transmission of heat from cavity to upper terminal by direct contact the heated 'r.

l fhile l in" e spoken of porcelain in the foregoing spec ication, of course insumat i' such as compressed balrelite, would be included have pro a ertures, a1 porcelain body to es, r away at interior thereof or the conductor therein.

same result that 1S obtained with igure 8, that is obtaineo.

1 tee prefer to turn the edges of the thimble .55 over upon the edges of the part J, as

( shown, to prevent possible short circuitinr. This thimble is preferably made sli htiy shorter than the depth of the cavity in which it fits so that when secured in place by 7' the turned over portion is force against the edge of the sleeve 0 to form tight joint. This construction permits of a tight joint which heat and expansion will not ailect. Bakelite cement or asbestos packing may be used under the flange to make a tighter, more cushioned, and leak-compression proo seat.

What 1 laiin is:

l In a spark plug structure a vertical central electrode and an electrode extending inward from said plug and turning vertically up ward parallel and adjacent to the mentioned electrode, the first named electrode terminating: in a disc below the upturned end of the electrode extending inward from the plug, said disc having a conical upper surface 25 A spark plug body a, the lower end of said body being formed into an annular peripheral fin which tapers from the body downward and forming the Wall surrounding a cavt-y in the lower surface substantially frustro-conical in 'fOlLl.

3. ln spark plug structure an insulat ing body (a) having an axial aperture therethrough and a cavity in its lower end a sleeve of conducting material engaging at its said thimble, Washenx and conductor in place sparking points passing orough the overturned edge of the thirobiea M In a spark plug structure, a plug of in saluting material, a sleeve of conducting material. engaging at its upperend around connectsaid plug and being adapted be the en 'ine cylinder; said t'rusto-conical Wall forming s cc d and a thirnble of i hav trusts-conical end Will A I a hot-spot the upper part of seio. under operating conditions:

5. In a spark ,plug structure, plug uluting material having cavity oW i end a conducting sleeve having l oart engage around said plug and L- i i .i i H aapt-ed he connected the engine cyl der and loving a hollow thiinble insulat 131g material fitting into said sleeve ano sale sleeve hving an end fitti; into saidcavity suri'ace to Q and presenting a frustro-conical the combustion chamber.

('3. 11 a spark plug structure, insulat- 121g body formed with a cavity end, said cavity having i'rustro-eonieai Walls, a plug bushing, the upper end clamoin iating body and an insulan thi in said bushing and in enged oveuto cover the edge o= and sparhi points pass-- ing ange.

'7. F n a snark lug structure; e combination 0 an insulating; body a ing a cav ity 1L8 end sleeve or conducti material. eng n at its upper end around the lower or said body and below end, and a thimble of thin insulating terial F of S1 in its lower a hm am said emit at 'hhe upper closadl and of said fihimh'lle, they lmwer or side Wall portion of saw 'iahimhie heing in contact with saidl sleeve to which it can lose heat mpicfiy, and the upper part of saicl thimhle in contact with said insulating b06137 to which the thimhie will lose "very slowly and there- &

fence have a high tempam'sure for the in matm'ial has a low rate of heat camdhmhiviizy the lower end of said thimhle W being 0pm t0 the: cnmhustion chamber.

In tes'nbimeny wherwf, I Sign this specifiwhim,

AMEL BBRGLUSKAJ 

